4.3. Allometry and Ontogeny
Unapparent skull asymmetries seem to be noticeable early in ontogeny in this species, although further studies may be necessary to confirm precisely at what point this begins. The presence of both shape and size asymmetry in dorsal and ventral skull views is undeniable in studied samples and more profoundly so in dorsal views (Table 1) despite similar level of significance after multivariate regression (Table 2). Results from the currently investigated samples (confirmed hypothesis number 2) demonstrated a persistence of directional asymmetry throughout ontogeny, we thus fail to accept the null hypothesis Further, skull shape changes concentrated collectively more on rostro-dorsal and caudal areas as growth advances, and are right side biased, (Fig. 4a and b) is suggestive of “handedness” (a tendency to use a side of the head more than the other naturally) in P. tricuspis. Confirmation for this ontogenetic trajectory is consistent with Esquerre et al (2017) and does not differ in other clades of pangolin species (Ferreira-Cardoso et al., 2020). Literature evidence, though scarce or non-existent in this species, suggested sex does not significantly influence shape, size notwithstanding as a covariate in the regression model of the skull (Ferreira-Cardoso et al., 2020). Allometric regressions of shape on size in existing works revealed a significant overlap of intercepts inP. tricuspis with all other species and between P. tetradactyla and P. javanicus only (Ferreira-Cardoso et al., 2020) this position postulates both a similarity and divergence in skull morphology of the species to provoke a cursory look at its characterization process (Table 2; Fig. 5).
Along the first axis (Figs. 4a and b), changes involved the posthion, nasal and maxillary regions whereas the second plane portray more shape changes synonymous with fronto-temporal sutures and the parieto-occipital areas, this observation was corroborated by Murphy et al. (2001b) in placental mammals. The correlation between morphology and modularity in the present investigation suggests that adult integration patterns are the result of selection pressures rather than historical constraints, and that developmental modularity played little constraining role in diversification (Fig. 6), similar to observations reported by Alfoldi et al. (2011) and Sanger et al. (2011) in studies involving other arboreal species; Anolis lizards (Anolis carolinensis ). The right and left ventro-lateral rims of the foramen magnum presented highest portions of individual shape diversities in ontogeny of this species as currently observed (Fig. 6), asymmetry in architecture of this foramen easily appeared by the 5th harmonic (Tables 3 and 4) despite the uninformative order of the angle of orientation of the EF position. Our inferences in this regard postulate dynamic developmental outcomes yielding foramen magnum phenotypes.